An electrical connector has an insulation covered electric wire having the end of a conductor, from which an insulator was removed. The electrical connector has a connection terminal conducted and connected with this end. The connection portion between the end of the conductor and the connection terminal is protected by a plastic connector housing (plastic cover), a polyvinyl chloride resin (PVC) mold, or the like.
With the conductor covered with the insulator, the impedance of the insulation covered electric wire is determined by the permittivity of the insulator. However, the insulator is removed from the terminal of the insulation covered electric wire, and the conductor is exposed to conduct and connect to the connection terminal of the electrical connector. Consequently, the impedance of this terminal becomes different from the impedance of the insulation covered portion.
Even if the connection portion between the end of the conductor and the connection terminal is covered with resin mold, the impedance of the connection portion is determined by complex factors, that is, the shape of the connection portion, the terminal configuration, the permittivity of mold resin material, and the like. Impedance control to a predetermined value is difficult, such as matching of the impedance of the connection portion to the impedance of the insulation covered portion.
Adding to this, a signal transmission cable for high-speed transmission called a high-speed cable is used by virtue of an acceleration of the transmission speed in the interface cable of a computer. This cable requires optimization of the impedance of the electrical connector as a non-conventional electrical characteristic. Thus, the impedance of an electrical connector is controlled to an appropriate predetermined value as needed.